Reliability and criterion-related validity of self-report of syphilis

Abstract

Objective: To determine the test-retest reliability, sensitivity and specificity, and criterion-related validity of the Risk Behavior Assessment (RBA) syphilis questions. The RBA is a standardized instrument that has been used in several studies of STDs in drug users.

Methods: For the test-retest reliability study, 219 injection drug users completed the RBA twice within a 48-hour period. To determine criterion-related validity, 207 individuals, who also completed the RBA, were tested with the rapid plasma reagin test (RPR), and 206 individuals were also tested with the Serodia Treponema pallidum particle agglutination test (TP-PA).

Results: The test-retest reliability for the question "How many times have you been told by a doctor or a nurse that you had syphilis?" was 0.78. The test-retest reliability for the question "In what year were you last treated for syphilis?" was 0.89. For the comparison of self-report with the RPR test, the sensitivity of self-report was 46.2% and the specificity was 95.7%. For the comparison of self-report with the TP-PA test, the sensitivity of self-report was 37% and the specificity was 97.7%.

Conclusions: Self-reports of syphilis infection history were found to have good reliability, excellent specificity, and moderate sensitivity. These characteristics need to be taken into account in any study using these self-report items.